Specific Aims: The usual approach to error reduction in health care begins with identification of errors that are then subjected to root cause analysis to uncover remediable causes. The use of reports by health care personnel concerning flawed processes and systemic factors that may be causing medical errors in their health care setting is a potentially promising innovative and complementary strategy for identifying correctable causes of errors. This application seeks to validate this new approach by pursuing the following specific aims: 1) To improve a previously developed instrument that directly identifies error-prone clinical processes and systemic factors contributing to errors in hospital emergency departments; 2) To validate this instrument in a network of emergency departments; 3) To improve understanding of the frequency and determinants of errors in emergency departments. Methods- To improve a previously constructed instrument, the investigators will conduct personal interviews, focus groups and literature reviews to produce a revised instrument that will be cognitively and psychometrically tested, and then administered to approximately 6800 personnel in a network of 85 emergency departments. The instrument will collect perceptions about compliance with standards of care for three common conditions (asthma, acute myocardial infarction, penetrating extremity trauma) and about the extent to which systemic contributors to safety are present in each ED. Approximately 210 chart reviews in each ED will detect actual rates of medical errors, measured both as failures to comply with standards of care and as occurrence of preventable adverse events and critical errors. The extent to which ED personnel reports are correlated with occurrence of errors on chart review will be determined in bivariate and multivariate analysis. This work will be conducted in a network of Eds that has extensive experience with multi-center clinical research and by a team of investigators from the Massachusetts General Hospital, Harvard Medical School, University of Colorado, and University of Texas. The team has experience in survey research, chart review, safety-related research, ED research and quality improvement.